[CentOS-virt] Why are bridges required?

Wed Jun 4 01:47:43 UTC 2014
lee <lee at yun.yagibdah.de>

Ilya Ponetayev <instenet at gmail.com> writes:

> You may create as many bridges as you want to have virtual interfaces,
> each bridge consisting only of connection to single VM, and handle
> traffic between bridges and between physical interfaces of host
> through iptables/iproute.

In that case, I`d prefer not to have bridges.  Things are easier to deal
with when you only have those network devices you actually need.
Dangling bridges seem to be pretty obsolete.

> IHMO bridging is the most proper and popular technique because it
> provides the most flexible configuration. Your VM sees NIC as Ethernet
> card (so with all L2 features), so either you can terminate this L2
> pipe with bridge in host, and perform L3/higher level handling, or you
> can use for example DHCP server on host binded to your bridge, or
> VLAN-handling config.

Bridges are cool when you actually need them.  That doesn`t mean that
they must be there when not needed.

Is there something I don`t understand which makes them always a
requirement?  If so, perhaps it would be a nice feature if we were able
to hide bridges we don`t need.

Knowledge is volatile and fluid.  Software is power.